Colorectal cancer remains one of the leading cause of cancer mortality in the United States. In 2006, there were approximately 55,170 estimated colorectal cancer (CRC) related deaths. Given early detection, early-stage colorectal cancer can be curable. However, given the insidious nature of colonic neoplasia, most patients are diagnosed when the cancer has evolved to a more advanced stage thus underscoring the need for effective screening of the at-risk population (e.g., those over 50 years of age) for early detection.
For example, existing colorectal cancer screening methods include fecal blood tests (FOBTs), endoscopy for direct visualization of the colon (e.g., flexible sigmoidoscopy or colonoscopy), and/or air-contrast barium enema. Although, the existing methods have been shown to demonstrate some efficacy in reducing colorectal cancer mortality and incidence, a large portion of the population does not undergo any endoscopic screening potentially due to patient and/or physician reluctance.
However, due to resource constraints and potential complications, it is impractical to perform colonoscopy on an entire at-risk population (e.g., those over the age of 50). In addition, for the general population the lifetime risk of developing CRC is approximately 6%. Thus performing colonoscopy on a large population to reach a relatively small subgroup of at risk population who may develop colonic neoplasia is cost and time inefficient.
Numerous techniques have been introduced for screening of colorectal cancer but have yet to demonstrate the robustness necessary for population screening. For example, reports of demonstrated performance of fecal DNA analysis were not statistically significant in multicenter trials. Further, the marked cost of fecal DNA analysis may be a barrier to wide spread usage.
From a radiological perspective, in single center studies, computed tomography colography (virtual colonoscopy) showed promise, unfortunately, the sensitivity demonstrated in multicenter trials have been unreliable. Furthermore, given the need for bowel cleansing and colonic air insufflation, there is no clear advantage in patient preference between CT colonography and colonoscopy. Given the high cost of CT colonography, it may be difficult to provide high quality CRC screening in a resource-constrained society.
Thus, there is a need to identify those more likely to harbor colonic neoplasia to target colonoscopy to these individuals. Such efforts can provide colonoscopy to a better defined set of patients more likely to be harboring neoplasia thereby sparing those patients who are unlikely to benefit from the cost, inconvenience, and potential complication of colonoscopy.
Pancreatic cancer is another leading cause of cancer death in the United States with most cancers diagnosed at a late, incurable stage. Existing approaches, including high-resolution imaging (MRI, CT, etc.), molecular diagnostics, and/or endoscopic cholangiopancreatography (ERCP), have not demonstrated the robustness in capability to detect pancreatic neoplasms sufficiently early to allow effective treatment.
Current imaging modalities as well as ERCP utilize detection of the presence of a mass lesion, and, therefore, even if the resolution of these tests is improved, the tumor detected may likely be biologically too advanced for cure. Despite years of research no clinically adequate molecular markers have been developed. The only route that currently has the potential for diagnosing pre-invasive cancer is through the pancreatic duct, where 90% of adenocarcinomas of the pancreas originate. Due to the potential for complications including pancreatitis (3-5% cases), as currently performed, ERCP may not be suitable for routine screening over successive points in time.